Runs rough when cold...WHY?
 

My 84 380SE runs rough when it is cold. It starts up fine and seems to run not too bad until you try and give it some gas. As soon as you step on the throttle it sputters and will even stall. If it runs for 5 mins and warms up it is alot better. It still wants to hesitate a bit though. Any ideas? It has a new cap on it. It is a 3.8l V8.
Thanx

Vacuum leak or the mixture is off cold.

Peter

Sounds like the control pressure/warmup regulator is causing a lean mixture when cold.

There is a small strainer in the return line from the regulator which blocks up and can cause hesitation and rough running when cold. Try cleaning that first. Otherwise get some fuel gauges and check all your pressures before throwing parts at it, it may be the regulator though.

Where abouts is the regulator? Where is the strainer located? Enigine compartment? Fuel tank?

Thanx

It's located in the engine bay in between the cylinder banks.

I don't have a picture to help show you where it is, but I've added a pic of a regulator.

The strainer in the fuel line fitting of the regulator (actually, it's the inlet side of the regulator not the return side)

Also I believe the car has an OVP (overvoltage protection) relay and if the fuse is blown in the OVP or the OVP is simply "bad", the engine will be running in FOM (fixed operating mode) which is "tuned" for normal operating temp, but car will run bad when cold (before it's warmed up), so check the fuse in the OVP relay.
Gilly